1. Field
Embodiments of the invention relate to inspection of nano-scale features of a sample. In particular, embodiments of the invention relate to a system and method for inspection of nano-scale features of a sample having regions of different characteristics using adaptive electrical probing.
2. Related Art
Scanning technologies are used to characterize and test nano-scale features of a sample for measurement, topographical mapping, testing etc., for example, for measuring features and testing performance of integrated circuits. Scanning technology instruments used to characterize and to test electrical performance of integrated circuits include atomic force prober (“AFP”) and scanning electron microscopy (“SEM”) based nanoprober. An AFP system is usually used in contact mode to obtain a topographical image of an integrated circuit. In contact mode, an AFP system uses a probe that is scanned over the various features of the sample in constant contact with the scanned area in order to obtain an elevation or “relief” image of the features that make up the sample, e.g., the integrated circuit. As the dimensions of the devices are shrinking with technology progress and are reaching nanometer scale, the constant force used by an AFP system to obtain an image results in damage to the devices of the integrated circuit that are scanned. Further, the force required to establish sufficient electrical contact to test the performance of one or more devices and/or components on an integrated circuit is such that damage to the integrated circuit occurs.
SEM based nanoprobing employs an electron microscopy to locate an area of interest. This approach may also damage devices and components used in the integrated circuit because the high-energy primary electrons generated by the SEM to obtain an image of the integrated circuit penetrate into the integrated circuit and generate undesired defects. This damage is especially problematic for smaller devices and components that have nanometer scale dimensions. Moreover, when the electron beam of the SEM is scanned over a dielectric, it charges the scanned area, which may interfere with the measurements. Thus, the use of an SEM at an area of an integrated circuit may modify the devices of interest obscuring the measurements and making the use of SEM based technologies problematic.